Duplex or dual-sided direct thermal printing of transaction documents or receipts is described in U.S. Pat. Nos. 6,784,906 and 6,759,366. The printers are configured to allow printing on both sides of sheet media moving along a feed path through the printer. In such printers a direct thermal print head is disposed on each side of the media feed path. A thermal print head faces an opposing platen across the feed path from the print head.
In direct thermal printing, a print head selectively applies heat to paper or other sheet media comprising a substrate with a thermally sensitive coating. The coating changes color when heat is transferred, by which “printing” is provided on the coated substrate. For dual-sided direct thermal printing, the sheet media substrate may be coated on both sides.
Duplex or dual-sided direct thermal printing has been described for providing variable information on both sides of a paper receipt, to save materials and to provide flexibility in providing information to customers. The printing could be driven electronically or by computer using a computer application program which directs dual-sided printing.
Given the general desirability of two-sided direct thermal printing for a variety of applications, qualified two-sided direct thermal imaging media or paper is needed.